diff --git a/ooi/api/base.py b/ooi/api/base.py
index 9e7d090..32370ec 100644
--- a/ooi/api/base.py
+++ b/ooi/api/base.py
@@ -16,6 +16,8 @@
 
 from ooi.wsgi import utils
 
+import webob.exc
+
 
 class Controller(object):
     def __init__(self, app, openstack_version):
@@ -31,3 +33,53 @@ class Controller(object):
         if body is not None:
             req.body = utils.utf8(body)
         return req
+
+    @staticmethod
+    def get_from_response(response, element, default):
+        """Get a JSON element from a valid response or raise an exception.
+
+        This method will extract an element a JSON response (falling back to a
+        default value) if the response has a code of 200, otherwise it will
+        raise a webob.exc.exception
+
+        :param response: The webob.Response object
+        :param element: The element to look for in the JSON body
+        :param default: The default element to be returned if not found.
+        """
+        if response.status_int == 200:
+            return response.json_body.get(element, default)
+        else:
+            raise exception_from_response(response)
+
+
+def exception_from_response(response):
+    """Convert an OpenStack V2 Fault into a webob exception.
+
+    Since we are calling the OpenStack API we should process the Faults
+    produced by them. Extract the Fault information according to [1] and
+    convert it back to a webob exception.
+
+    [1] http://docs.openstack.org/developer/nova/v2/faults.html
+
+    :param response: a webob.Response containing an exception
+    :returns: a webob.exc.exception object
+    """
+    exceptions = {
+        400: webob.exc.HTTPBadRequest,
+        401: webob.exc.HTTPUnauthorized,
+        403: webob.exc.HTTPForbidden,
+        404: webob.exc.HTTPNotFound,
+        405: webob.exc.HTTPMethodNotAllowed,
+        406: webob.exc.HTTPNotAcceptable,
+        409: webob.exc.HTTPConflict,
+        413: webob.exc.HTTPRequestEntityTooLarge,
+        415: webob.exc.HTTPUnsupportedMediaType,
+        429: webob.exc.HTTPTooManyRequests,
+        501: webob.exc.HTTPNotImplemented,
+        503: webob.exc.HTTPServiceUnavailable,
+    }
+    code = response.status_int
+    message = response.json_body.popitem()[1].get("message")
+
+    exc = exceptions.get(code, webob.exc.HTTPInternalServerError)
+    return exc(explanation=message)
diff --git a/ooi/api/compute.py b/ooi/api/compute.py
index c5983eb..75810b7 100644
--- a/ooi/api/compute.py
+++ b/ooi/api/compute.py
@@ -38,7 +38,7 @@ class Controller(ooi.api.base.Controller):
         tenant_id = req.environ["keystone.token_auth"].user.project_id
         req = self._get_req(req, path="/%s/servers" % tenant_id)
         response = req.get_response(self.app)
-        servers = response.json_body.get("servers", [])
+        servers = self.get_from_response(response, "servers", [])
         occi_compute_resources = self._get_compute_resources(servers)
 
         return collection.Collection(resources=occi_compute_resources)
@@ -63,7 +63,7 @@ class Controller(ooi.api.base.Controller):
                                 }}))
         response = req.get_response(self.app)
         # We only get one server
-        server = response.json_body.get("server", {})
+        server = self.get_from_response(response, "server", {})
 
         # The returned JSON does not contain the server name
         server["name"] = params["/occi/infrastructure"]
@@ -77,13 +77,13 @@ class Controller(ooi.api.base.Controller):
         # get info from server
         req = self._get_req(req, path="/%s/servers/%s" % (tenant_id, id))
         response = req.get_response(self.app)
-        s = response.json_body.get("server", {})
+        s = self.get_from_response(response, "server", {})
 
         # get info from flavor
         req = self._get_req(req, path="/%s/flavors/%s" % (tenant_id,
                                                           s["flavor"]["id"]))
         response = req.get_response(self.app)
-        flavor = response.json_body.get("flavor", {})
+        flavor = self.get_from_response(response, "flavor", {})
         res_tpl = templates.OpenStackResourceTemplate(flavor["name"],
                                                       flavor["vcpus"],
                                                       flavor["ram"],
@@ -93,7 +93,7 @@ class Controller(ooi.api.base.Controller):
         req = self._get_req(req, path="/%s/images/%s" % (tenant_id,
                                                          s["image"]["id"]))
         response = req.get_response(self.app)
-        image = response.json_body.get("image", {})
+        image = self.get_from_response(response, "image", {})
         os_tpl = templates.OpenStackOSTemplate(image["id"],
                                                image["name"])
 
diff --git a/ooi/api/query.py b/ooi/api/query.py
index 50a2469..58a0aa1 100644
--- a/ooi/api/query.py
+++ b/ooi/api/query.py
@@ -29,7 +29,7 @@ class Controller(base.Controller):
         tenant_id = req.environ["keystone.token_auth"].user.project_id
         req = self._get_req(req, path="/%s/flavors/detail" % tenant_id)
         response = req.get_response(self.app)
-        flavors = response.json_body.get("flavors", [])
+        flavors = self.get_from_response(response, "flavors", [])
         occi_resource_templates = []
         if flavors:
             for f in flavors:
@@ -44,7 +44,7 @@ class Controller(base.Controller):
         tenant_id = req.environ["keystone.token_auth"].user.project_id
         req = self._get_req(req, path="/%s/images/detail" % tenant_id)
         response = req.get_response(self.app)
-        images = response.json_body.get("images", [])
+        images = self.get_from_response(response, "images", [])
         occi_os_templates = []
         if images:
             for i in images:
diff --git a/ooi/tests/fakes.py b/ooi/tests/fakes.py
index fb0569d..dee3035 100644
--- a/ooi/tests/fakes.py
+++ b/ooi/tests/fakes.py
@@ -18,6 +18,10 @@ import json
 import uuid
 
 import webob.dec
+import webob.exc
+
+import ooi.wsgi
+import ooi.wsgi.utils
 
 
 tenants = {
@@ -156,6 +160,35 @@ def fake_query_results():
     return result
 
 
+class FakeOpenStackFault(ooi.wsgi.Fault):
+    _fault_names = {
+        400: "badRequest",
+        401: "unauthorized",
+        403: "forbidden",
+        404: "itemNotFound",
+        405: "badMethod",
+        406: "notAceptable",
+        409: "conflictingRequest",
+        413: "overLimit",
+        415: "badMediaType",
+        429: "overLimit",
+        501: "notImplemented",
+        503: "serviceUnavailable"}
+
+    @webob.dec.wsgify()
+    def __call__(self, req):
+        code = self.wrapped_exc.status_int
+        fault_name = self._fault_names.get(code)
+        explanation = self.wrapped_exc.explanation
+        fault_data = {
+            fault_name: {
+                'code': code,
+                'message': explanation}}
+        self.wrapped_exc.body = ooi.wsgi.utils.utf8(json.dumps(fault_data))
+        self.wrapped_exc.content_type = "application/json"
+        return self.wrapped_exc
+
+
 class FakeApp(object):
     """Poor man's fake application."""
 
@@ -205,8 +238,9 @@ class FakeApp(object):
     def _do_get(self, req):
         try:
             ret = self.routes[req.path_info]
-        except Exception:
-            raise
+        except KeyError:
+            exc = webob.exc.HTTPNotFound()
+            ret = FakeOpenStackFault(exc)
         return ret
 
 
diff --git a/ooi/tests/middleware/test_compute_controller.py b/ooi/tests/middleware/test_compute_controller.py
index 27255d3..0621cef 100644
--- a/ooi/tests/middleware/test_compute_controller.py
+++ b/ooi/tests/middleware/test_compute_controller.py
@@ -14,6 +14,8 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import uuid
+
 import mock
 
 from ooi.tests import fakes
@@ -115,6 +117,15 @@ class TestComputeController(test_middleware.TestMiddleware):
             self.assertExpectedResult(expected, resp)
             self.assertEqual(200, resp.status_code)
 
+    def test_vm_not_found(self):
+        tenant = fakes.tenants["foo"]
+
+        app = self.get_app()
+        req = self._build_req("/compute/%s" % uuid.uuid4().hex,
+                              tenant["id"], method="GET")
+        resp = req.get_response(app)
+        self.assertEqual(404, resp.status_code)
+
     def test_create_vm(self):
         tenant = fakes.tenants["foo"]
 
diff --git a/ooi/tests/middleware/test_middleware.py b/ooi/tests/middleware/test_middleware.py
index 1b58dfa..7763f8a 100644
--- a/ooi/tests/middleware/test_middleware.py
+++ b/ooi/tests/middleware/test_middleware.py
@@ -16,6 +16,8 @@
 
 import mock
 import webob
+import webob.dec
+import webob.exc
 
 from ooi.tests import base
 from ooi.tests import fakes
@@ -63,6 +65,16 @@ class TestMiddleware(base.TestCase):
         result = self._build_req("/", "tenant").get_response(self.get_app())
         self.assertEqual(404, result.status_code)
 
+    def test_400_from_openstack(self):
+        @webob.dec.wsgify()
+        def _fake_app(req):
+            exc = webob.exc.HTTPBadRequest()
+            resp = fakes.FakeOpenStackFault(exc)
+            return resp
+
+        result = self._build_req("/-/", "tenant").get_response(_fake_app)
+        self.assertEqual(400, result.status_code)
+
 
 class TestMiddlewareTextPlain(TestMiddleware):
     """OCCI middleware test with Accept: text/plain."""